34786 Federal Register / Vol. 63, No. 123 / Friday, June 26, 1998 /Rules and Regulations

likely to disrupt the operation of the

system under test, based on its design

characteristics. For example, flight

control systems may be susceptible to 3

Hz square wave modulation while the

video signals for electronic display

systems may be susceptible to 400 Hz

sinusoidal modulation. If the worst-case

modulation is unknown or cannot be

determined, default modulations may be

used. Suggested default values are a 1

KHz sine wave with 80 percent depth of

modulation in the frequency range from

10 KHz to 400 MHz and 1 KHz square

wave with greater than 90 percent depth

of modulation from 400 MHz to 18 GHz.

For frequencies where the unmodulated

signal would cause deviations from

normal operation, several different

modulating signals with various

waveforms and frequencies should be

applied.

Applicants must perform a

preliminary hazard analysis to identify

electrical/electronic systems that

perform critical functions. The term

‘‘critical’’ means those functions whose

failure would contribute to or cause an

unsafe condition that would prevent the

continued safe flight and landing of the

helicopter. The systems identified by

the hazard analysis as performing

critical functions are required to have

HIRF protection. A system may perform

both critical and noncritical functions.

Primary electronic flight display

systems and their associated

components perform critical functions

such as attitude, altitude, and airspeed

indications. HIRF requirements would

apply only to the systems that perform

critical functions.

Acceptable system performance

would be attained by demonstrating that

the critical function components of the

system under consideration continue to

perform their intended function during

and after exposure to required

electromagnetic fields. Deviations from

system specifications may be acceptable

but must be independently assessed by

the FAA on a case-by-case basis.

TABLE 1.—VFR ROTORCRAFT FIELD

STRENGTH VOLTS/METER

Frequency Peak Average

10–100 KHz .............. 150 150

100–500 .................... 200 200

500–2000 .................. 200 200

2–30 MHz .................. 200 200

30–100 ...................... 200 200

100–200 .................... 200 200

200–400 .................... 200 200

400–700 .................... 730 200

700–1000 .................. 1400 240

1–2 GHz .................... 5000 250

2–4 ............................ 6000 490

4–6 ............................ 7200 400

TABLE 1.—VFR ROTORCRAFT FIELD

STRENGTH VOLTS/METER—Continued

Frequency Peak Average

6–8 ............................ 1100 170

8–12 .......................... 5000 330

12–18 ........................ 2000 330

18–40 ........................ 1000 420

TABLE 2.—IFR ROTORCRAFT FIELD

STRENGTH VOLTS/METER

Frequency Peak Average

10–100 KHz .............. 50 50

100–500 .................... 50 50

500–2000 .................. 50 50

2–30 MHz .................. 100 100

30–70 ........................ 50 50

70–100 ...................... 50 50

100–200 .................... 100 100

200–400 .................... 100 100

400–700 .................... 700 50

700–1000 .................. 700 100

1–2 GHz .................... 2000 200

2–4 ............................ 3000 200

4–6 ............................ 3000 200

6–8 ............................ 1000 200

8–12 .......................... 3000 300

12–18 ........................ 2000 200

18–40 ........................ 600 200

Applicability

As previously discussed, this special

condition is applicable to Model AS–

365 N3 helicopters. Should Eurocopter

France apply at a later date for a change

to the type certificate to include another

model incorporating the same novel or

unusual design feature, the special

condition would apply to that model as

well under the provisions of

§ 21.101(a)(1).

Conclusion

This action affects only certain novel

or unusual design features on one model

series of helicopters. It is not a rule of

general applicability and affects only

the applicant who applied to the FAA

for approval of these features on the

helicopters.

The substance of this special

condition has been subjected to the

notice and comment procedures in

several prior instances and has been

derived without substantive change

from those previously issued. It is

unlikely that prior public comment

would result in a significant change

from the substance contained herein.

For this reason and because a delay

would significantly affect the

certification of the helicopter, which is

imminent, the FAA has determined that

prior public notice and comment are

unnecessary and impracticable, and

good cause exists for adopting this

special condition upon issuance. The

FAA is requesting comments to allow

interested persons to submit views that

may not have been submitted in

response to the prior opportunities for

comment described above.

List of Subjects in 14 CFR Part 21 and

29

Aircraft, Air transportation, Aviation

safety, Rotorcraft, Safety.

The authority citation for these

special conditions is as follows: 42 USC

7572; 49 USC. 106(g), 40105, 40113,

44701–44702, 44704, 44709, 44711,

44713, 44715, 45303.

The Special Condition

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the following special

condition is issued as part of the type

certification basis for Eurocopter France

Model AS 365 N3 ‘‘Dauphin’’

helicopters.

Protection for Electrical and Electronic

Systems From High Intensity Radiated

Fields

Each system that performs critical

functions must be designed and

installed to ensure that the operation

and operational capabilities of these

critical functions are not adversely

affected when the helicopter is exposed

to high intensity radiated fields external

to the helicopter.

Issued in Fort Worth, Texas, on June 17,

1998.

Eric Bries,

Acting Manager, Rotorcraft Directorate

Aircraft Certification Service, ASW–100.

[FR Doc. 98–16960 Filed 6–25–98; 8:45 am]

BILLING CODE 4910–13–U

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 27

[Docket No. SW001; Special Conditions No.

27–001–SC]

Special Conditions: Eurocopter Model

AS–350 B3 ‘‘Ecureuil’’ Helicopters, Full

Authority Digital Engine Control

(FADEC)

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Final special condition; request

for comments.

SUMMARY: This special condition is

issued for the Eurocopter Model AS–350

B3 ‘‘Ecureuil’’ helicopters. These

helicopters will have a novel or unusual

design feature associated with the Full

Authority Digital Engine Control
Federal Register / Vol. 63, No. 123 / Friday, June 26, 1998 /Rules and Regulations 34787

(FADEC). The applicable airworthiness

regulations do not contain adequate or

appropriate safety standards to protect

systems that perform critical control

functions, or provide critical displays,

from the effects of high-intensity

radiated fields (HIRF). This special

condition contains the additional safety

standards that the Administrator

considers necessary to ensure that

critical functions of systems will be

maintained when exposed to HIRF.

DATES: The effective date of this special

condition is April 30, 1998. Comments

must be received on or before August

25, 1998.

ADDRESSES: Comments on this special

condition may be mailed in duplicate

to: Federal Aviation Administration,

Office of the Regional Counsel,

Attention: Rules Docket No. SW001,

Fort Worth, Texas 76193–0007 or

deliver in duplicate to the Office of the

Regional Counsel at 2601 Meacham

Blvd., Fort Worth, Texas 76137.

Comments must be marked: Rules

Docket No. SW001. Comments may be

inspected in the Rules Docket

weekdays, except Federal holidays,

between 8:30 a.m. and 4:00 p.m.

FOR FURTHER INFORMATION CONTACT:

Carroll Wright, FAA, Rotorcraft

Directorate, Regulations Group, Fort

Worth, Texas 76193–0111; telephone

817–222–5120, fax 817–222–5961.

SUPPLEMENTARY INFORMATION: The FAA

has determined that notice and

opportunity for prior public comment

hereon are impracticable because these

procedures would significantly delay

issuance of the design approval and

thus delivery of the affected aircraft. In

addition, notice and opportunity for

prior public comment are unnecessary

since the substance of these special

conditions has been subject to the

public comment process in several prior

instances with no substantive comments

received. The FAA therefore finds that

good cause exists for making this special

condition effective upon issuance.

Comments Invited

Interested persons are invited to

submit such written data, views, or

arguments as they may desire.

Communications should identify the

regulatory docket or special condition

number and be submitted in duplicate

to the address specified above. All

communications received on or before

the closing date for comments will be

considered by the Administrator. The

special condition may be changed in

light of the comments received. All

comments received will be available in

the Rules Docket for examination by

interested persons, both before and after

the closing date for comments. A report

summarizing each substantive public

contact with FAA personnel concerning

this rulemaking will be filed in the

docket. Commenters wishing the FAA to

acknowledge receipt of their comments

submitted in response to this special

condition must include a self-addressed,

stamped postcard on which the

following statement is made:

‘‘Comments to Rules Docket No.

SW001.’’ The postcard will be date

stamped and returned to the

commenter.

Background

On June 18, 1997, Eurocopter applied

for an amendment to Type Certificate

(TC) No. H9EU to include the new

Model AS–350 B3 ‘‘Ecureuil’’

helicopter. The Model AS–350 B3

‘‘Ecureuil’’ helicopter, which is a

derivative of the AS–350 B/B1/B2

versions currently approved under TC

No. H9EU, is a normal category fivepassenger helicopter powered by a

Turbomeca Arriel 2B engine with

FADEC. The Model AS–350 B3 is

derived from the Model AS–350 B2 with

the following main modifications: (1)

Turbomeca Arriel 2B engine with digital

engine control system; (2) Powerplant

instruments on Liquid Crystal Display;

and (3) AS–355 N type tail rotor.

Type Certification Basis

Under the provisions of 14 CFR

21.101, Eurocopter must show that the

Model AS–350 B3 ‘‘Ecureuil’’ helicopter

meets the applicable provisions of the

regulations incorporated by reference in

TC No. H9EU or the applicable

regulations in effect on the date of

application for the change to the Model

AS–350 B3. The regulations

incorporated by reference in the type

certificate are commonly referred to as

the ‘‘original type certification basis.’’

The regulations incorporated by

reference in H9EU are as follows:

§ 21.29 and 14 CFR part 27, effective

February 1, 1965, plus Amendments 27–

1 through 27–10. In addition, the

certification basis includes certain

special conditions and equivalent safety

findings that are not relevant to this

special condition.

If the Administrator finds that the

applicable airworthiness regulations do

not contain adequate or appropriate

safety standards for these helicopters

because of a novel or unusual design

feature, special conditions are

prescribed under the provisions of

§ 21.16.

In addition to the applicable

airworthiness regulations and special

conditions, the Model AS–350 B3 must

comply with the noise certification

requirements of 14 CFR part 36; and the

FAA must issue a finding of regulatory

adequacy pursuant to section 611 of

Public Law 92–574, the ‘‘Noise Control

Act of 1972.’’

Special conditions, as appropriate, are

issued in accordance with § 11.49, as

required by §§ 11.28 and 11.29(b), and

become part of the type certification

basis in accordance with § 21.101(b)(2).

Special conditions are initially

applicable to the model for which they

are issued. Should the type certificate

for that model be amended later to

include any other model that

incorporates the same novel or unusual

design feature, or should any other

model already included on the same

type certificate be modified to

incorporate the same novel or unusual

design feature, the special conditions

would also apply to the other model

under the provisions of § 21.101(a)(1).

Novel or Unusual Design Features

The Eurocopter Model AS–350 B3

‘‘Ecureuil’’ helicopters will incorporate

the following novel or unusual design

features: Electrical, electronic, or

combination of electrical electronic

(electrical/electronic) systems, such as

FADEC, that will be performing

functions critical to the continued safe

flight and landing of the helicopter.

FADEC is an electronic device that

performs the functions of engine

control.

Discussion

The Eurocopter Model AS–350 B3

‘‘Ecureuil’’ helicopter, at the time of

application, was identified as having

modifications that incorporate one and

possibly more electrical/electronic

systems, such as FADEC. After the

design is finalized, Eurocopter will

provide the FAA with a preliminary

hazard analysis that will identify any

other critical functions, required for safe

flight and landing, performed by the

electrical/electronic systems.

Recent advances in technology have

given rise to the application in aircraft

designs of advanced electrical/

electronic systems that perform critical

functions. These advanced systems

respond to the transient effects of

induced electrical current and voltage

caused by HIRF incident on the external

surface of the helicopter. These induced

transient currents and voltages can

degrade the performance of the

electrical/ electronic systems by

damaging the components or by

upsetting the systems’ functions.

Furthermore, the electromagnetic

environment has undergone a

transformation not envisioned by the

current application of § 27.1309(a).
34788 Federal Register / Vol. 63, No. 123 / Friday, June 26, 1998 /Rules and Regulations

Higher energy levels radiate from

operational transmitters currently used

for radar, radio, and television. Also, the

number of transmitters has increased

significantly.

Existing aircraft certification

requirements are inappropriate in view

of these technological advances. In

addition, the FAA has received reports

of some significant safety incidents and

accidents involving military aircraft

equipped with advanced electrical/

electronic systems when they were

exposed to electromagnetic radiation.

The combined effects of the

technological advances in helicopter

design and the changing environment

have resulted in an increased level of

vulnerability of the electrical/electronic

systems required for the continued safe

flight and landing of the helicopter.

Effective measures to protect these

helicopters against the adverse effects of

exposure to HIRF will be provided by

the design and installation of these

systems. The following primary factors

contributed to the current conditions:

(1) increased use of sensitive electronics

that perform critical functions, (2)

reduced electromagnetic shielding

afforded helicopter systems by

advanced technology airframe materials,

(3) adverse service experience of

military aircraft using these

technologies, and (4) an increase in the

number and power of radio frequency

emitters and the expected increase in

the future.

The FAA recognizes the need for

aircraft certification standards to keep

pace with the developments in

technology and environment and, in

1986, initiated a high priority program

to (1) determine and define

electromagnetic energy levels; (2)

develop and describe guidance material

for design, test, and analysis; and (3)

prescribe and promulgate regulatory

standards.

The FAA participated with industry

and airworthiness authorities of other

countries to develop internationally

recognized standards for certification.

The FAA and airworthiness

authorities of other countries have

identified two levels of the HIRF

environment that a helicopter could be

exposed to, one environment for VFR

operations and a different environment

for IFR operations. While the HIRF

rulemaking requirements are being

finalized, the FAA is adopting a special

condition for the certification of aircraft

that employ electrical/electronic

systems that perform critical control

functions, or provide critical displays.

The accepted maximum energy levels

that civilian helicopter system

installations must withstand for safe

operation are based on surveys and

analysis of existing radio frequency

emitters. This special condition will

require the helicopters’ electrical/

electronic systems and associated

wiring to be protected from these energy

levels. These external threat levels are

believed to represent the worst-case

exposure for a helicopter operating

under VFR or IFR.

Compliance with HIRF requirements

will be demonstrated by tests, analysis,

models, similarity with existing

systems, or a combination of these

methods. Service experience alone will

not be acceptable since such experience

in normal flight operations may not

include an exposure to HIRF. Reliance

on a system with similar design features

for redundancy, as a means of

protection against the effects of external

HIRF, is generally insufficient because

all elements of a redundant system are

likely to be concurrently exposed to the

radiated fields.

This special condition will require the

systems that perform critical control

functions, or provide critical displays as

installed in the aircraft, to meet certain

standards based on either a defined

HIRF environment or a fixed value

using laboratory tests. Control system

failures and malfunctions can more

directly and abruptly contribute to a

catastrophic event than display system

failures and malfunctions. Therefore it

is considered appropriate to require

more rigorous HIRF verification

methods for critical control systems

than for critical display systems.

The applicant may demonstrate that

the operation and operational

capabilities of the installed electrical/

electronic systems that perform critical

functions are not adversely affected

when the aircraft is exposed to the

defined HIRF test environment.

The FAA has determined that the test

environment defined in Table 1 is

acceptable for critical control functions

in helicopters. The test environment

defined in Table 2 is acceptable for

critical display systems in helicopters.

The applicant may also demonstrate

by a laboratory test that the electrical/

electronic systems that perform critical

control, or provide critical displays can

withstand a peak electromagnetic field

strength in a frequency range of 10 KHz

to 18 GHz. If a laboratory test is used to

show compliance with the defined HIRF

environment, no credit will be given for

signal attenuation due to installation. A

level of 100 volts per meter (v/m) is

appropriate for critical display systems.

A level of 200 v/m is appropriate for

critical control functions. Laboratory

test levels are defined according to

RTCA/DO–160D Section 20 Category W

(100 v/m and 150 mA) and Category Y

(200 v/m and 300 mA). As defined in

DO–160D Section 20, the test levels are

defined as the peak of the root means

squared (rms) envelope. As a minimum,

the modulations required for RTCA/

DO–160D Section 20 Categories W and

Y will be used. Other modulations

should be selected for the signal most

likely to disrupt the operation of the

system under test, based on its design

characteristics. For example, flight

control systems may be susceptible to 3

Hz square wave modulation while the

video signals for electronic display

systems may be susceptible to 400 Hz

sinusoidal modulation. If the worst-case

modulation is unknown or cannot be

determined, default modulations may be

used. Suggested default values are a 1

KHz sine wave with 80 percent depth of

modulation in the frequency range from

10 KHz to 400 MHz and 1 KHz square

wave with greater than 90 percent depth

of modulation from 400 MHz to 18 GHz.

For frequencies where the unmodulated

signal would cause deviations from

normal operation, several different

modulating signals with various

waveforms and frequencies should be

applied.

Applicants must perform a

preliminary hazard analysis to identify

electrical/electronic systems that

perform critical functions. The term

‘‘critical’’ means those functions whose

failure would contribute to or cause an

unsafe condition that would prevent the

continued safe flight and landing of the

helicopters. The systems identified by

the hazard analysis as performing

critical functions are required to have

HIRF protection. A system may perform

both critical and noncritical functions.

Primary electronic flight display

systems and their associated

components perform critical functions

such as attitude, altitude, and airspeed

indications. HIRF requirements would

apply only to the systems that perform

critical functions, including control and

display.

Acceptable system performance

would be attained by demonstrating that

the critical function components of the

system under consideration continue to

perform their intended function during

and after exposure to required

electromagnetic fields. Deviations from

system specifications may be acceptable

but must be independently assessed by

the FAA on a case-by-case basis.

TABLE 1.—VFR ROTORCRAFT FIELD

STRENGTH VOLTS/METER

Frequency Peak Average

10–100 KHz .................. 150 150
Federal Register / Vol. 63, No. 123 / Friday, June 26, 1998 /Rules and Regulations 34789

TABLE 1.—VFR ROTORCRAFT FIELD

STRENGTH VOLTS/METER—Continued

Frequency Peak Average

100–500 ........................ 200 200

500–2000 ...................... 200 200

2–30 MHz ...................... 200 200

30–100 .......................... 200 200

100–200 ........................ 200 200

200–400 ........................ 200 200

400–700 ........................ 730 200

700–1000 ...................... 1400 240

1–2 GHz ........................ 5000 250

2–4 ................................ 6000 490

4–6 ................................ 7200 400

6–8 ................................ 1100 170

8–12 .............................. 5000 330

12–18 ............................ 2000 330

18–40 ............................ 1000 420

TABLE 2.—IFR ROTORCRAFT FIELD

STRENGTH VOLTS/METER

Frequency Peak Average

10–100 KHz .................. 50 50

100–500 ........................ 50 50

500–2000 ...................... 50 50

2–30 MHz ...................... 100 100

30–70 ............................ 50 50

70–100 .......................... 50 50

100–200 ........................ 100 100

200–400 ........................ 100 100

400–700 ........................ 700 50

700–1000 ...................... 700 100

1–2 GHz ........................ 2000 200

2–4 ................................ 3000 200

4–6 ................................ 3000 200

6–8 ................................ 1000 200

8–12 .............................. 3000 300

12–18 ............................ 2000 200

18–40 ............................ 600 200

Applicability

As previously discussed, this special

condition is applicable to the Model

AS–350 B3 helicopter. Should

Eurocopter apply at a later date for a

change to the type certificate to include

another model incorporating the same

novel or unusual design feature, the

special condition would apply to that

model as well under the provisions of

§ 21.101(a)(1).

Conclusion

This action affects only certain novel

or unusual design features on one model

helicopter. It is not a rule of general

applicability and affects only the

applicant who applied to the FAA for

approval of these features on the

helicopter.

The substance of this special

condition has been subjected to the

notice and comment procedure in

several prior instances and has been

derived without substantive change

from those previously issued. It is

unlikely that prior public comment

would result in a significant change

from the substance contained herein.

For this reason and because a delay

would significantly affect the

certification of the helicopter, which is

imminent, the FAA has determined that

prior public notice and comment are

unnecessary and impracticable, and

good cause exists for adopting this

special condition upon issuance. The

FAA is requesting comments to allow

interested persons to submit views that

may not have been submitted in

response to the prior opportunities for

comment described above.

List of Subjects in 14 CFR Parts 21 and

27

Aircraft, Air transportation, Aviation

safety, Rotorcraft, Safety.

The authority citation for this special

condition is as follows: 42 U.S.C. 7572;

49 U.S.C. 106(g), 40105, 40113, 44701–

44702, 44704, 44709, 44711, 44713,

44715, 45303.

The Special Condition

Accordingly, pursuant to the

authority delegated to me by the

Administrator, the following special

condition is issued as part of the type

certification basis for Eurocopter Model

AS–350 B3 ‘‘Ecureuil’’ helicopters.

Protection for Electrical and Electronic

Systems from High Intensity Radiated

Fields

Each system that performs critical

functions must be designed and

installed to ensure that the operation

and operational capabilities of these

critical functions are not adversely

affected when the helicopter is exposed

to high intensity radiated fields external

to the helicopter.

Issued in Fort Worth, Texas, on April 30,

1998.

Eric Bries,

Acting Manager, Rotorcraft Directorate,

Aircraft Certification Service.

[FR Doc. 98–16959 Filed 6–25–98; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97–SW–39–AD; Amendment

39–10630; AD 98–13–39]

RIN 2120–AA64

Airworthiness Directives; Eurocopter

France Model AS 332C, L, and L1

Helicopters

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a

new airworthiness directive (AD),

applicable to Eurocopter France Model

AS 332C, L, and L1 helicopters that

requires initial and repetitive

inspections of the tail rotor shaft

flapping hinge retainers (retainers) for

cracks. This amendment is prompted by

a report of high vibrations occurring on

a helicopter while in service due to a

cracked retainer. The actions specified

by this AD are intended to detect cracks

on the retainers that could lead to high

tail rotor vibrations, loss of tail rotor

control, and subsequent loss of control

of the helicopter.

EFFECTIVE DATE: July 31, 1998.

FOR FURTHER INFORMATION CONTACT: Mr.

Mike Mathias, Aerospace Engineer,

FAA, Rotorcraft Directorate, Rotorcraft

Standards Staff, 2601 Meacham Blvd.,

Fort Worth, Texas 76137, telephone

(817) 222–5123, fax (817) 222–5961.

SUPPLEMENTARY INFORMATION: A

proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to

include an airworthiness directive (AD)

that is applicable to Eurocopter France

Model AS 332C, L, and L1 helicopters

was published in the Federal Register

on April 1, 1998 (63 FR 15791). That

action proposed to require initial and

repetitive inspections of the retainers for

cracks.

Interested persons have been afforded

an opportunity to participate in the

making of this amendment. No

comments were received on the

proposal or the FAA’s determination of

the cost to the public. The FAA has

determined that air safety and the

public interest require the adoption of

the rule as proposed.

The FAA estimates that 4 helicopters

of U.S. registry will be affected by this

AD, that it will take approximately 0.5

work hours per helicopter to accomplish

the required actions, and that the

average labor rate is $60 per work hour.

Required parts, if replacement of the

retainers on the tail rotor blades is

necessary, would cost approximately

$56,900 per helicopter. Based on these

figures, the total cost impact of the AD

on U.S. operators is estimated to be

$252,080, assuming that the retainers on

the tail rotor blades are replaced on all

4 helicopters and each helicopter is dye

penetrant inspected 200 times per year.

The regulations adopted herein will

not have substantial direct effects on the

States, on the relationship between the

national government and the States, or

on the distribution of power and

responsibilities among the various

levels of government. Therefore, in